Doubt from parabola

Question no 68

Answer is equals 4.

Answer is 8 given in answer key

Help @Achyut_2020 , @Prajwal_2020_1

since vertex is shifted in a line parallel to x=y
therefore ,let the new vertex be (a,4+a) with "a" being a simple parameter
since no other change is made to the parabola
substitute y=y-a and x=x-a
and we know one of the root to be +2 substitute in parabola eqn to get "a"
the find the other root to get the answer

2 Likes

answer is 8. Vertex will become of form (h,h+4). So parabola can be written as (x-h)^2=(h+4-y). Now put B(2,0) in eqn and h will come out to be 5.

1 Like